Trends in Thumb Carpometacarpal Interposition Arthroplasty in the United States, 2005–2011
We conducted a study to investigate current trends in carpometacarpal (CMC) interposition arthroplasty across time, sex, age, and region of the United States; per-patient charges and reimbursements; and the association between this procedure and concomitantly performed carpal tunnel syndrome (CTS) and carpal tunnel release (CTR).
Patients who underwent CMC interposition arthroplasty (N = 41,171) were identified in a national database. Between 2005 and 2011, the number of patients who had CMC interposition arthroplasty increased 46.2%. Females had the procedure more frequently than males at all time points, though the percentage of patients who were male increased throughout the study period. Of the patients who had CMC interposition arthroplasty, 40.9% also had a diagnosis of CTS. Between 15.5% and 17.3% of these patients had CTR performed concomitantly.
Despite a lack of evidence that thumb CMC interposition arthroplasty is superior to other surgical treatment options, the number of patients who are having this procedure has increased significantly. The impetus for these trends requires additional investigation.
Increases in procedure incidence were noted in all regions of the United States, but the largest percentage increase occurred in the Northeast. Despite this increase, the Northeast also had significantly lower CMC interposition arthroplasty incidence compared with all other regions and with the average procedure incidence throughout the study period—demonstrating some regional bias as to treatment of thumb CMC-OA. Unfortunately, because of database limitations and lack of specific CPT codes for other treatment options for thumb CMC-OA, we cannot ascertain if other types of surgery are more frequently used in the Northeast.
CTS and thumb CMC-OA often coexist.37 The estimated incidence of concomitant CTS in patients with CMC-OA is between 4% and 43%, but the rate of concomitant CTR and CMC interposition arthroplasty was not previously characterized in the literature.38,39 Results of the present study supported these findings; 41% of patients who underwent CMC interposition arthroplasty in our study also had a CTS diagnosis, compared with 43% in the 246-patient study by Florack and colleagues.38 We also found that 16% to 17% of patients who underwent CMC interposition arthroplasty underwent concomitant CTR; this rate remained consistent throughout the study period.
Our study demonstrated that, compared with CMC interposition arthroplasties, significantly fewer thumb CMC arthrodesis procedures were performed in the same Medicare population during the same period. Furthermore, the number of thumb CMC arthrodesis procedures declined yearly, with an overall decrease of 19% from 2005 to 2011. In a recent single-blinded, randomized trial, Vermeulen and colleagues40 compared thumb CMC arthrodesis and trapeziectomy with LRTI. They found superior patient satisfaction and significantly lower complication rates in women who underwent LRTI versus arthrodesis. The study was terminated prematurely because of these complications and thus was underpowered to determine differences in specific outcome measures. Previous studies comparing arthrodesis and interposition arthroplasties reported inconsistent outcomes. Hart and colleagues41 found no significant differences in pain or function between CMC arthrodesis and LRTI at a mean 7-year follow-up in a level II randomized controlled trial. Hartigan and colleagues15 reached similar conclusions in their retrospective comparison of the procedures. Without clear evidence supporting arthrodesis over interposition arthroplasty, the majority of surgeons favor interposition arthroplasty for thumb CMC-OA. Among Medicare patients, use of thumb CMC arthrodesis continues to fall.
This national database study had several limitations, which are common to all studies using the PearlDiver database22,42-47:
1. The power of the analysis depended on the quality of available data. Potential sources of error included accuracy of billing codes, and miscoding or noncoding by physicians.46
2. Although we used this database to try to accurately represent a large population of interest, we cannot guarantee the database represented a true cross section of the United States.
3. For the Medicare population, the PearlDiver database indexes data only in 7-year increments. Although the study period was long enough to detect significant trends, some data may not be accurately captured over a 7-year period.
4. Patients were not randomized to a treatment group.
5. The PearlDiver database does not include any clinical outcome data. Therefore, we cannot comment on the efficacy of the reported evaluations and interventions.
6. There is no specific CPT code for thumb CMC interposition arthroplasty. However, we are unaware of a CMC interposition arthroplasty performed for any area besides the thumb. Theoretically, the study population can include a negligible percentage of patients who had interposition arthroplasty of a CMC joint other than the thumb.
7. The database cannot be searched for use of thumb CMC-OA surgical techniques other than CMC interposition arthroplasty or arthrodesis, as isolated trapeziectomy, volar ligament reconstruction, implant arthroplasty, and metacarpal osteotomy lack specific CPT codes.
Conclusion
Thumb CMC-OA is a common entity among Medicare patients. There are numerous surgical options for cases that have failed conservative treatment. Despite the lack of evidence that thumb CMC interposition arthroplasty is superior to other surgical options, the number of patients who had this procedure increased 46% during the 2005–2011 study period. Although the majority of patients who undergo CMC interposition arthroplasty are female, the percentage of male patients has increased significantly. More than 40% of patients who have CMC interposition arthroplasty are also diagnosed with CTS, and 16% to 17% of patients who have CMC interposition arthroplasty will have a concomitant CTR. CMC arthrodesis is used in significantly fewer patients of Medicare age, and its use has been declining.
